An artificial tooth is a dental crown material preliminarily provided to a dentist or a dental technician in an anatomical form of a human tooth for use in manufacture of a plate denture. The artificial tooth is available in several types of shape, size and color, and is selected appropriately to be used depending on the condition of defect of the patient and the treatment plan.
A general fabricating method of a plate denture and a method of using the artificial tooth are briefly described below.
First, a model is fabricated by pouring plaster into a model of the oral shape of a patient which is taken by using an impression material such as silicone, agar or arginic acid.
The manufactured plaster model is installed in a device called an articulator having hinges similar to the temporomandibular joint of the patient. The artificial tooth selected according to the patient is positioned on the model while considering the entire balance and the occlusion of the upper and lower jaws. Then, the defect portion of peripheral tissues such as gum is formed by using paraffin wax so that a prototype of an entire denture called a wax denture is completed.
This denture with the model is embedded in plaster, the wax is removed to obtain a plaster model. In the plaster model, a denture based resin such as PMMA is injected, cured and hardened. The resin is taken out from the plaster model, polished and adjusted so that a denture is completed.
The plate denture is classified into a partial denture and a complete denture. The partial denture is a prosthetic appliance for compensating for the function and aesthetics of lost portion of dental root in oral in which natural teeth are partially remaining. The complete denture is a prosthetic appliance for covering the jaw losing all of the crown and root called an edentulous jaw.
A healthy person usually has 28 teeth or 32 teeth at maximum in oral. Since there exist combinations of processes of losing these teeth and various treatment plans by dentures, artificial teeth are used in a tremendous number of cases. Therefore, it has been demanded to satisfy various requirements by a limited number of types.
In particular, when occlusion of artificial teeth is required in upper and lower edentulous jaws, or dentulous jaws having similar degree of defects to the edentulous jaws, artificial teeth of upper and lower sets are used. At this time, for smooth operation, the artificial teeth are required to design the distribution of dimensions of tooth by booth so as to bite in a proper vertical direction preliminarily and to be positioned easily. However, actually such artificial teeth are rare, and the technician must decide the position while correcting the shape individually. Thus, it has been taking much time and labor to make the denture.
Patent document 1 discloses prosthetic posterior teeth formed to avoid mutual contact in lateral motion of mastication of buccal cusp. Patent document 2 discloses prosthetic posterior teeth in which the lower cusp of the maxillary posterior teeth bites and contacts with the fossa of the mandibular posterior teeth, and the buccal cusp of the mandibular posterior teeth bites and contacts with the fossa of the maxillary posterior teeth. Patent document 3 discloses prosthetic posterior teeth in which the buccal projection of the mandibular posterior teeth engages with the cleft of the maxillary posterior teeth, and the lingual projection of the maxillary posterior teeth engages with the longitudinal cleft of the mandibular posterior teeth.
In any of the patent documents, however, nothing is specified about the three-dimensional positional relation or contact region of all cusps and pits. Hence, even if artificial teeth of the mandibular posterior teeth are arranged without making gap, when attempted to position such that the artificial teeth of the mandibular posterior teeth bite the corresponding artificial teeth of the maxillary posterior teeth tooth by tooth, the artificial teeth of the adjacent maxillary posterior teeth may interfere with each other or a gap may be formed. Therefore, it was required to adjust and correct repeatedly.    Patent document 1: Japanese Patent Application Laid-Open No. 11-290347
Patent document 2: Japanese Patent Application Laid-Open No. 2002-177301
Patent document 3: Japanese Patent Publication No. 3747251